Conventionally, automobiles and other vehicles have been driven primarily and almost exclusively via gasoline fueled technologies. An operator of the vehicle may engage the vehicle in a non-operating state employing mostly battery power (i.e. via electric power). After which, the vehicle may be placed in a mode in which the relevant mechanisms for ensuring the vehicle's motion is driven primarily by a fuel, such as gasoline.
Because the motion of the vehicle was primarily driven by gasoline, the conservation of battery power during the gasoline-driven mode was not a priority. However, in recent times, developers of vehicles have moved towards the creation of a multi-mode vehicle. Aspects of the vehicle responsible for the motion of the vehicle may now be operated by a combination of a battery power and gas power.
In certain cases, a vehicle may employ a combination of the various ways to power and drive a motor vehicle. One of the newly implemented techniques is a start-stop system. The start-stop system automatically shuts down and restarts an internal combustion engine to reduce the amount of time the engine spends idling. This reduces fuel consumption, and therefore, increases the overall efficiency of how a vehicle operates.
For example, if the vehicle stops at a traffic light, or in a traffic jam, the engine does not have to be in a state of continual operation. In this case, the start-stop system may actuate, and the vehicle electrical system may be kept running by electric power (rather than fuel). By employing this technology, vehicles may operate in a more efficient manner while reducing harmful effects to the environment.
One of the elements employed to aid in the start-stop system is a boost circuit. The boost circuit essentially detects that the voltage has dropped below a predetermined value (for example, 6.8V), and applies a compensation voltage to a voltage output node (Vout) to compensate for the voltage drop.
Once the voltage on the Vin node rises above a certain value, the boost circuit is disabled.
FIG. 1 illustrates an example of a conventional implementation of a start-stop system 100. The system 100 includes a vehicle battery 110, a boost circuit 120, and a microcontroller 130.
The vehicle battery 110 serves to provide power to various elements and parts in a vehicle, and has ground node 112, and is connected to the boost circuit 120 via node 111. In the context shown in FIG. 1, the vehicle battery 110 serves to power the boost circuit 120 from node 111 to an input node 128. The boost circuit 120 includes various circuit elements, such as elements 121-125. The explanation of the elements 121-125 will be omitted as the boost circuit 120 shown in FIG. 1 is known to one of ordinary skill in the art. The control of the boost circuit 120 is accomplished by applying a sequence of voltage pulses with a particular duty cycle to a transistor gate 126, and a supply 129. The supply 129 is a signal that controls the voltage/charge pumping associated with boost circuit 120. Essentially, if the vehicle battery 110 is loaded by a demand for more power, the supply 129 applies a voltage pulse sequence to the gate 126, thereby allowing boost circuit 120 to operate to provide boost voltage.
The microprocessor 130 monitors the status 131 of the boost circuit 120 (i.e. determines how much voltage the boost circuit 120 is generating or needs to generate), and disables or enable the boost circuit 120 via control input 132. In this way, the microprocessor 130 may effectively determine whether the boost circuit 120 is turned on/off to boost the amount of voltage required for the operation of a vehicle in a stop mode of a start-stop system.
In essence, with a motor in a start-stop system 100 as shown above is in a stop situation (i.e. idled or stopped), if an operator of the vehicle engages a gas pedal, a boost of current is usually required to aid in the restart of the engine. This energy is drawn from the battery 110 shown above, which leads to the battery 110 being heavily loaded, and potentially causing spikes. Since various elements of the vehicle may rely on the battery 110 (for example, the lighting, sound, HVAC, etc)—various operations may be suspended, frustrated, or altered—thereby effecting the overall experience with a vehicle in a start-stop system.
The conventional system above employs the status pin 131 to determine whether to enable the boost circuit 120. Thus, the boost circuit 120 may continually run in two situations, when a crank is detected (i.e. a gas pedal is asserted to leave a stop mode), or when the battery voltage is detected as low. However, each of the states may require a different amount of boost voltage/power for a different time amount. Employing the aspects disclosed above with FIG. 1, providing different amounts of boost voltage/power for different time amounts is not possible.